The present invention relates to pump systems, and more particularly, to pump systems for lubricating a fan drive gear system in gas turbine engines.
In many gas turbine engines, a low pressure spool includes a low pressure turbine connected to and driving a low pressure compressor, and a high pressure spool includes a high pressure turbine connected to and driving a high pressure compressor. A main pump is typically driven by the high pressure spool, connected through gearing, and is used to pump lubricating liquid to all engine components that require lubrication. When the high pressure spool stops rotating or rotates at a reduced rpm (revolutions per minute), the main supply pump will ordinarily provide little or no liquid to engine components.
In some gas turbine engines, a fan at the front of the engine is connected to the low pressure spool through a fan drive gear system. When the high pressure spool stops rotating or rotates at a reduced rpm, the fan drive gear system can continue rotating. For example, wind may rotate the fan and corresponding gears and bearings while the aircraft is parked on the ground or during an in-flight engine shutdown. Certain gears and bearings can be damaged by non-lubricated operation.